/*
 * @(#)CombinerParameter.java
 *
 * Copyright 2005 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1. Redistribution of source code must retain the above copyright notice,
 *      this list of conditions and the following disclaimer.
 * 
 *   2. Redistribution in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * Neither the name of Sun Microsystems, Inc. or the names of contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MICROSYSTEMS, INC. ("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
 * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
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 *
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 */

package org.wso2.balana.combine;

import org.wso2.balana.Balana;
import org.wso2.balana.Indenter;
import org.wso2.balana.ParsingException;
import org.wso2.balana.UnknownIdentifierException;

import org.wso2.balana.attr.AttributeFactory;
import org.wso2.balana.attr.AttributeValue;

import java.io.OutputStream;
import java.io.PrintStream;

import org.w3c.dom.Node;

/**
 * Represents a single named parameter to a combining algorithm. Parameters are
 * only used by XACML 2.0 and later policies.
 * 
 * @since 2.0
 * @author Seth Proctor
 */
public class CombinerParameter {

	// the name of this parameter
	private String name;

	// the value of this parameter
	private AttributeValue value;

	/**
	 * Creates a new CombinerParameter.
	 * 
	 * @param name
	 *            the parameter's name
	 * @param value
	 *            the parameter's value
	 */
	public CombinerParameter(String name, AttributeValue value) {
		this.name = name;
		this.value = value;
	}

	/**
	 * Returns a new instance of the <code>CombinerParameter</code> class based
	 * on a DOM node. The node must be the root of an XML CombinerParameterType.
	 * 
	 * @param root
	 *            the DOM root of a CombinerParameterType XML type
	 * 
	 * @throws ParsingException
	 *             if the CombinerParameterType is invalid
	 */
	public static CombinerParameter getInstance(Node root)
			throws ParsingException {
		// get the name, which is a required attribute
		String name = root.getAttributes().getNamedItem("ParameterName")
				.getNodeValue();

		// get the attribute value, the only child of this element
		AttributeFactory attrFactory = Balana.getInstance()
				.getAttributeFactory();
		AttributeValue value = null;

		try {
			value = attrFactory.createValue(root.getFirstChild());
		} catch (UnknownIdentifierException uie) {
			throw new ParsingException(uie.getMessage(), uie);
		}

		return new CombinerParameter(name, value);
	}

	/**
	 * Returns the name of this parameter.
	 * 
	 * @return the name of this parameter
	 */
	public String getName() {
		return name;
	}

	/**
	 * Returns the value provided by this parameter.
	 * 
	 * @return the value provided by this parameter
	 */
	public AttributeValue getValue() {
		return value;
	}

	/**
	 * Encodes this parameter into its XML representation and writes this
	 * encoding to the given <code>OutputStream</code> with indentation.
	 * 
	 * @param output
	 *            a stream into which the XML-encoded data is written
	 * @param indenter
	 *            an object that creates indentation strings
	 */
	public void encode(OutputStream output, Indenter indenter) {
		PrintStream out = new PrintStream(output);
		String indent = indenter.makeString();

		out.println(indent + "<CombinerParameter ParameterName=\"" + getName()
				+ "\">");
		indenter.in();

		getValue().encode(output, indenter);

		out.println(indent + "</CombinerParameter>");
		indenter.out();
	}

}
